Method and apparatus for forming patterned coated films

ABSTRACT

An apparatus and method of uniformly patterning electro-luminescent layer or layers of an electro-luminescent device such as a photovoltaic cell or an OLED includes solvating and wiping the layer(s) in a tangential direction.

BACKGROUND OF INVENTION

This invention relates to an electro-luminescent device, such as anorganic light emitting diode. More particularly, the invention relatesto a method of uniformly patterning an electro-luminescent layer of suchelectro-luminescent devices.

Electro-active devices, such as organic light emitting diodes (referredhereinafter to as “OLEDs”), are widely used in organic transistors, fuelcell components, microelectronics processing, microanalytical testprocedures, and in specialty electronics. One of the features of suchdevices is an electro-luminescent layer, formed from photo-sensitivematerials, that emits light on receiving an electrical impulse. In orderto facilitate miniaturization, conform to device geometry, and maximizeelectro-luminescent yield, the electro-luminescent layer must often bepatterned to various textures, topography, and geometries.

Electro-luminescent layer patterning has been conventionally performedusing stamping or laser ablation. In stamping, a pattern is imprintedupon the layer using mechanical force upon a patterned die or a stampinghead, whereas in laser ablation, a patterned photomask covers the areato be patterned while the remaining area is selectively etched using alaser beam.

One problem associated with such patterning of electro-luminescentlayers is that stamping leaves behind a substantial amount of materialresidue on the layer surface. Patterning by stamping also does notguarantee uniform, reproducible, and precise patterning over largespecimens. While laser ablation may yield uniform, reproducible, andprecisely patterned surfaces, the process needs high vacuum conditions,produces excessive debris around the patterned area, is expensive, andcannot be performed on large specimens or in fieldwork.

The current methods for patterning an electro-luminescent layer inelectro-active devices use mechanical or laser-beam techniques that donot enable patterned surfaces to be patterned to precision in minimalturnaround times. Therefore, what is needed is an electro-active devicehaving an electro-luminescent layer that is precisely and quicklypatterned to uniform thickness. What is also needed is a method forpatterning such an electro-luminescent layer that is applicable to avariety of material compositions with a variety of solvating species.What is also needed is a patterning method that is effectivelyindependent of the processing or forming history of theelectroluminescent film.

BRIEF SUMMARY OF THE INVENTION

The present invention meets these and other needs by providing apatterned electro-luminescent layer of substantially uniform thicknessand a method of forming such a patterned electro-luminescent layer on asubstrate. Different kinds of electro-luminescent layers can bepatterned by this method. An electro-luminescent device, such as aphotovoltaic cell or OLED, having at least such one electro-luminescentlayer, is also provided. The invention also includes an apparatus formaking an electro-luminescent layer by selectively removing at least onecoating from a surface of a substrate.

Accordingly, one aspect of the invention is to provide anelectro-luminescent device. The electro-luminescent device comprises atleast one electrode and an electro-luminescent layer disposed on the atleast one electrode. The electro-luminescent layer comprises anelectro-luminescent polymeric material and has a first pattern disposedon a surface adjacent to the at least one electrode and has asubstantially uniform thickness.

A second aspect of the invention is to provide an electro-luminescentlayer for an electro-luminescent device. The electro-luminescent layercomprises an electro-luminescent polymeric material. Theelectro-luminescent layer is patterned and has a substantially uniformthickness, and is formed by forming a continuous sheet ofelectro-luminescent polymeric material and removing a portion of thecontinuous sheet by wiping a surface of the continuous sheet in adirection that is tangential to the surface.

A third aspect of the invention is to provide an electro-luminescentdevice. The electro-luminescent device comprises at least one electrode;an electro-luminescent layer; and at least one conductive layer disposedbetween the at least one electrode and the electro-luminescent layer.The electro-luminescent layer comprises an electro-luminescent polymericmaterial, is patterned, and has a substantially uniform thickness. Theelectro-luminescent layer is formed by forming a continuous sheet ofelectro-luminescent polymeric material and removing a portion of thecontinuous sheet by wiping a surface of the continuous sheet in adirection that is tangential to the surface.

A fourth aspect of the invention is to provide a light source comprisinga plurality of electro-luminescent devices. Each electro-luminescentdevice comprises at least one electrode; an electro-luminescent layer,and at least one conductive layer disposed between the at least oneelectrode and the electro-luminescent layer. The electro-luminescentlayer comprises an electro-luminescent polymeric material, and ispatterned and has a substantially uniform thickness. Theelectro-luminescent layer is formed by forming a continuous sheet ofelectro-luminescent polymeric material and removing a portion of thecontinuous sheet by wiping a surface of the continuous sheet in adirection that is tangential to the surface.

A fifth aspect of the invention is to provide a method of selectivelyremoving at least one coating from a surface of a substrate. The methodcomprises the steps of: providing a substrate having the coatingdisposed on the surface; tangentially contacting a portion of thecoating with a wiping head; and wiping the portion with the wiping headto remove a portion of the coating from the substrate.

A sixth aspect of the invention is to provide an apparatus forselectively removing at least one coating from a surface of a substrate.The apparatus comprises: a means for supplying the substrate having theat least one coating; a wiping head for removing a portion of thecoating, wherein the wiping head tangentially contacts the coating; anda means for collecting the substrate after removing the portion.

A seventh aspect of the invention is to provide a wiping head forremoving a portion of at least one coating disposed on a surface of asubstrate. The wiping head comprises a contact surface for contactingand removing the portion of the coating. The contact surfacetangentially contacts the portion and has a predetermined geometry.

These and other aspects, advantages, and salient features of the presentinvention will become apparent from the following detailed description,the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a light source comprising a plurality ofelectro-luminescent devices on an optical panel;

FIG. 2 is a cross-sectional view of an electro-luminescent device;

FIG. 3 is a schematic view of one embodiment of an electro-luminescentdevice with its constituent patterns;

FIG. 4 is a schematic view of a second embodiment of a patternedelectro-luminescent device having a coated portion and uncoated portion;

FIG. 5 is a schematic view of an embodiment for removing a portion ofcontinuous sheet by wiping;

FIG. 6 is a schematic cross-sectional view of the contact surface of awiping head of the present invention;

FIG. 7A is a schematic view of a method of selectively removing at leastone coating from a surface of a substrate; and

FIG. 7B is a second schematic view of a method of selectively removingat least one coating from a surface of a substrate.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, like reference characters designate likeor corresponding parts throughout the several views shown in thefigures. It is also understood that terms such as “top”, “bottom”,“outward”, “inward”, and the like are words of convenience and are notto be construed as limiting terms.

Referring to the drawings in general and to FIG. 1 in particular, itwill be understood that the illustrations are for the purpose ofdescribing a preferred embodiment of the invention and are not intendedto limit the invention thereto.

Visible light sources produce light in different ways. Such devices maycomprise different components and mechanisms for producing light andsome sources may produce light more efficiently than others. Many lightsources are made of electro-luminescent materials arranged as coatingsor films upon an electro-active substrate (often called an electrode).Consequently, the film may be patterned or textured to suit designrequirements.

Common methods of film patterning, such as ink jet printing, deposit thecoating one drop at a time, by creating polyimide wells to position thedrop on the film surface. This method is commonly used in pixels fordisplays. Films may also be patterned or textured using methods such as,but not limited to, screen printing, gravure printing, flexographicprinting, offset lithographic printing, spin coating, spray coating,meniscus coating, and dip coating. However, it is difficult to disposeand pattern coating layers of uniform thickness using such methods withsubsequent solvent deposition in which the solvent creates a crater orchannel upon drying. One embodiment of the present invention discloses apatterning method applicable to large area devices with coatings ofuniform thickness. A common approach to producing patternedelectro-luminescent film is to selectively remove portions of theelectro-luminescent coating from a continuous film of theelectro-luminescent material. This is conventionally done using laserablation, plasma etching, scratching the film surface, tape lifting, andlifting off under high temperature or pressure using a die or stamp.However, there are certain disadvantages associated with each of thesemethods. For instance, laser ablation and plasma etching focus on smallworking areas of the specimen, and the cost for scaling up the processcan be very high. Scratching requires plowing through the continuouscoating with a stiff stylus, which can potentially damage the underlyinglayers or substrates. Stamping and lifting with a rubbery die offer anaffordable but qualitatively unacceptable solution. The liftoff processcan be uniquely related to the materials of construction of the die andmay result in incomplete coating removal with residues deposited on thestamped area. The residues can also affect the final properties andperformance of the electro-luminescent device.

The present invention provides a process to selectively remove a portionof a continuous electro-luminescent film and to produce a sharplypatterned electro-luminescent film.

The invention also provides a process to remove coating material from acontinuous electro-luminescent film via wiping with a ‘moistened’ softhead. In another embodiment, the wiping head contains solvents thatsolvate (or moisten, using aqueous or non-aqueous solvents) theelectro-luminescent film. A tangential wiping action using the wipinghead assists in removing the solvated area.

In another embodiment, the invention also provides a solvent system thatenables removal of portions of multiple layers of film in a single step.The multiple layers may either be identical or distinct from each other.

In one embodiment of the present invention, shown in FIG. 1, a lightsource 50 comprises several different electro-luminescent devices 100,102, 104, and 106 mounted on an optical panel 75. Theelectro-luminescent devices may differ from each other in geometry,processing, spatial assembly, and function. A cross-sectional view ofone such electro-luminescent device 100 is schematically shown in FIG.2. Electro-luminescent device 100 includes electrode 110 and anelectro-luminescent layer 120 disposed thereon. The electro-luminescentlayer 120 has a first pattern 130 disposed on a surface adjacent toelectrode 110. Electro-luminescent layer 120 is made from anelectro-luminescent polymeric material and has a substantially uniformthickness. In another embodiment, shown in FIG. 3, theelectro-luminescent device 100 further comprises a conductive layer 140disposed between the electrode 110 and the electro-luminescent layer120. The conductive layer 140 has a second pattern 150 disposed on asurface adjacent to electro-luminescent layer 120. In yet anotherembodiment, the first pattern 130 is identical to the second pattern150. Conductive layer 140 comprises at least one of poly(3,4-ethylenedioxythiophene) (also referred to hereinafter as “PEDOT”),poly (3,4-propylenedioxythiophene) (also referred to hereinafter as“PProDOT”), polystyrenesulfonate (PSS), polyvinylcarbazole (alsoreferred to hereinafter as “PVK”), combinations thereof, and the like.Electrode 110 comprises at least one of a metal, indium tin oxide,silicon, and combinations thereof.

In the embodiment shown in FIG. 4, electro-luminescent layer 120 isdisposed on one of conductive layer 140 and comprises a first pattern130. First pattern 130 comprises at least one coated portion 160 havinga coated surface area and at least one uncoated portion 170 having anuncoated surface area, wherein the at least one uncoated portion 170intersects the coated portion 160 to form a first coated area 162 and asecond coated area 164. Coated surface area 160 is frequently greaterthan the uncoated surface area 170. Additionally, the uncoated portion170 comprises at least one channel 180 that cuts through coated portion160 such that the channel 180 has a plurality of walls 190. Each of theplurality of walls 190 has a boundary width 220 of less than 20% of thewidth of channel 180. Coated portion 160 has a thickness in a range fromabout 50 nm to about 150 nm.

The electro-luminescent layer 120 comprises a polymeric material suchas, but not limited to, conjugated polymers, such as polyfluorenes,polyphenylenes (PPPs), and poly para-(phenylenevinylenes) (PPVs). Theconductive layer 140 comprises at least one of poly(3,4-ethylenedioxythiophene) (commonly known as “PEDOT”), poly(3,4-propylenedioxythiophene) (also referred to herein as “PProDOT”),polystyrenesulfonate (also referred to herein as “PSS”),polyvinylcarbazole (also referred to herein as “PVK”), and combinationsthereof. In other embodiments of the invention, electro-luminescentdevice 100 further comprises at least one additional polymer layer thatperforms conductive, emissive, charge injection, and charge blockingfunctions in the electro-luminescent device 100. Electrode 110 comprisesa high work function material capable of forming ohmic contact with theupper adjacent layer (conductive layer 140). Electrode 110 comprises atleast one of: indium tin oxide; tin oxide; zinc oxide; fluorinated zincoxide; tin doped zinc oxide; cadmium tin oxide; gold; a conductivepolymer comprising at least one of PEDOT, PProDOT, PSS, PVK; andcombinations thereof. In other embodiments of the invention, electrode110 is supported by a substrate material such as, but not limited to, apolycarbonate, a polyolefin, a polyester, a polyimide, a polysulfone, anacrylate, glass, metal foil, and combinations thereof.

In another embodiment of the present invention, an electro-luminescentlayer 120 is disclosed for an electro-luminescent device 100. Theelectro-luminescent layer 120 comprises an electro-luminescent polymericmaterial. The electro-luminescent layer 120 is patterned and has asubstantially uniform thickness 200, and is formed by forming acontinuous layer 115 of the electro-luminescent polymeric material andremoving a portion of the continuous layer 115 by wiping a surface 118of the continuous layer 115 in a direction that is tangential 210 to thesurface, as shown in FIG. 5.

Electro-luminescent layer 120 is disposed adjacent to at least oneconductive layer 140. Electro-luminescent layer 120 possesses a pattern130 comprising at least one coated portion 160 having a coated surfacearea and at least one uncoated portion 170 having an uncoated surfacearea, wherein the at least one uncoated portion intersects the coatedportion to form a first coated area 162 and a second coated area 164.Typically, the coated surface area is greater than the uncoated surfacearea. Additionally, the uncoated portion 170 comprises at least onechannel 180 that cuts through coated portion 160 such that channel 180has a plurality of walls 190 each of the plurality of walls 190 has aboundary width 220 of less than 20% of the width of channel 180. Coatedsurface area 160 has a thickness in a range from about 50 nm to about150 nm.

In one embodiment, electro-luminescent layer 120 is made from acontinuous polymer sheet 115. The continuous polymer sheet 115 is formedby depositing a polymeric film, such as PEDOT or the like, on acontinuous sheet of a substrate, patterning the polymeric film, andbaking the polymeric film at a temperature between about 50° C. andabout 200° C. The actual baking temperature depends upon the polymersubstrate that is used to support the continuous polymer sheet 115. Thepolymeric film is then coated with an electro-luminescent material toform electro-luminescent layer 120 on the polymer film, and theelectro-luminescent layer 120 is then patterned. The steps of patterningthe polymeric film, patterning electro-luminescent layer 120, and bakingmay be performed in any sequential order. For example, application ofpolymeric and electro-luminescent films, patterning, and baking mayproceed according to any of the sequences shown in Table 1. TABLE 1Different, non-limiting embodiments of the present invention showingvarious process methods in PEDOT film application and patterning. In thetable, “EL” refers to the application of electro-luminescent film. SI.Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 1. apply pattern drybake apply pattern EL dry PEDOT PEDOT EL 2. apply pattern dry bake applydry pattern PEDOT PEDOT EL EL 3. apply dry pattern bake apply pattern ELdry PEDOT PEDOT EL 4. apply dry pattern bake apply dry pattern PEDOTPEDOT EL EL 5. apply dry bake pattern apply pattern EL dry PEDOT PEDOTEL 6. apply dry bake pattern apply dry pattern PEDOT PEDOT EL EL 7.apply dry bake apply pattern dry pattern PEDOT EL EL PEDOT 8. apply drybake apply dry pattern EL pattern PEDOT EL PEDOT 9. apply dry bake applydry pattern EL PEDOT EL and PEDOT simultaneously 10. apply dry applypattern dry pattern bake PEDOT EL EL PEDOT 11. apply dry apply drypattern pattern bake PEDOT EL EL PEDOT 12. apply dry apply dry patternEL bake PEDOT EL and PEDOT simultaneously 13. apply dry apply patterndry bake pattern PEDOT EL EL PEDOT 14. apply dry apply dry bake patternEL pattern PEDOT EL PEDOT 15. apply dry apply dry bake pattern EL PEDOTEL and PEDOT simultaneously

To facilitate film removal over a selected area of theelectro-luminescent film, a portion of the continuous polymer sheet 115is solvated by at least one of water, methanol, ethanol, isopropanol,acetone, toluene, xylene, and combinations thereof. The surface of thesolvated portion of continuous polymer sheet 115 is wiped by wiping head230 remove a portion of at least one film, thereby patterning the film,or films. Wiping head 230 comprises at least one of a sponge, elastomer,thermoplastic, thermoset, fiber mat, porous material, polyurethanerubber, synthetic rubber, natural rubber, silicones,polydimethylsiloxane (PDMS), textured materials, and combinationsthereof.

In one embodiment of the invention, the solvating species are selectedfor removing a single layer of film with each wiping action withoutdamaging underlying layers. In another embodiment, the solvating speciesare selected to facilitate removal of multiple layers with each wiping.For example, an electro-luminescent film in a two-layer structure can bepatterned using xylene as a solvent without damaging a PEDOT layerunderneath. In yet another embodiment, two polymer layers can also beremoved in one step with a solvent system containing water and xylene.In this particular embodiment, isopropanol is used to facilitate mixingof water and xylene to yield a homogeneous solution.

In another embodiment of the claimed invention, a method of selectivelyremoving at least one coating from a surface of a substrate is disclosedand generally shown in FIGS. 7A and 7B. The method comprises the stepsof: providing substrate 410 having at least one coating 420 disposed ona surface of the substrate 410; tangentially contacting a portion 460 ofcoating 420 with wiping head 230; and wiping the portion 460 with wipinghead 230 in a direction 210 that is tangential to the surface to removea portion of coating 420 from substrate 410. Coating 420 may be either awet coating or a dry coating. Alternatively, coating 420 may includeboth wet and dry regions. In one embodiment, coating 420 is baked ontothe surface of substrate 410. Wiping head 230 is at least one of a drywiping head and a wiping head moistened with solvent 250. Solvent 250comprises at least one of a polar solvent, a nonpolar solvent, andcombinations thereof. Non-limiting examples of solvent 250 includewater, methanol, ethanol, isopropanol, acetone, toluene, xylene, andcombinations thereof. The choice of solvent 250 depends entirely on thecoating to be removed. In one embodiment, wiping head 230 is moistenedby injecting solvent 250 into the head 230 while wiping head 230 wipesportion 460 of coating 120. In another embodiment, wiping head 230 ismoistened prior to wiping by at least one of dipping wiping head 230into a bath containing solvent 250, soaking wiping head 230 in a bathcontaining solvent 250, spraying either wiping head 230 or portion 460with solvent 250, or the like.

Solvent 250 may be either polar or non-polar. For each polymer coatingmaterial, there are usually three solubility parameters that account forthe non-polar, polar, and hydrogen bonding strength of the polymer.Similarly, there are three corresponding solubility parameters for eachsolvent. The best solvent for a polymer is one having solubilityparameters that match those of the polymer.

Example b 1

Removal of coating comprising of polymers having extreme solubilitycharacteristics (i.e. co-existence of both very polar and non-polarmaterials).

In typical instances, the electro-luminescent layer comprises both (i) aconductive polymer coating, such as PEDOT, which is very polar anddissolves only in hydrogen-bonding solvents like water, and (ii) a lightemitting polymer coating that is non-polar, which dissolves only innon-polar solvents such as toluene or xylene. In order to removemultiple polymer coatings having extremely divergent solubilitycharacteristics in a single wipe, suitable solvents for each polymer aredispersed in a third solvent to produce a homogeneous solution. Thethird, or dispersing, solvent is selected from a number of solvents,such as, but not limited to, alcohols (such as isopropanol, ethanol,methanol, and the like), ketones (such as acetone, methyl ethyl ketone,and the like), acetates, ethers, methylene chloride, or any solventhaving intermediate solubility parameters. The solvent ratings for atypical light-emitting plastic and PEDOT are listed in Table 1. TABLE 1Solvent rating for polymers (1 = low solubility or insoluble; 5 = highsolubility). Solvent Light-emitting plastic PEDOT Water 1 5 Methanol 2 2Ethanol 3 1 Isopropanol 3 1 Acetone 1 1 Toluene 5 1 Xylene 5 1

Example 2

Removal of coating comprising polymers having similar solubilitycharacteristics (i. e., with intermediate solubility parameters).

Good solvents include either one-component systems having solubilityparameters that closely match the solubility parameters of the polymerfilm (or films), or multi-component solvent systems having effectivesolubility parameters that match the solubility parameters of thepolymer. The solvents in the multi-component system do not necessarilyhave to be a good solvent for the polymer. For example, neither CCl₄ norethanol are good individual solvents for polymethylmethacrylate (PMMA),but a binary mixture of CCl₄ and ethanol is a good solvent for PMMAbecause the effective solubility parameter of the mixture matches thatof PMMA.

Example 3

Wiping Example—Selective removal of top coating without damagingunderlying layer.

In this example, a PEDOT layer is spin coated onto an indium tin oxide(ITO) coated glass substrate and baked at 200° C. for 1 hour. A layer oflight emitting plastic (i.e., electro-luminescent layer) is thenspin-coated on top of the PEDOT layer. The patterned area is wiped bysolvent assisted wiping (SAW) in which xylene was the only solvent usedto remove portions of the electro-luminescent layer.

Example 4

Wiping Example—Simultaneous removal of both coating layers The PEDOTlayer is spin coated onto an indium tin oxide (ITO) coated glasssubstrate and baked at 200° C. for 1 hour. A layer of light emittingplastic (or electro-luminescent layer) is spin-coated on top of thePEDOT layer. The patterned area is wiped by solvent assisted wiping(SAW) with a solvent mixture consisting of water, isopropanol, andxylene so as to remove both PEDOT and electro-luminescent layers.

Wiping head 230 comprises at least one of a sponge, an elastomer, athermoplastic, a thermoset, a fiber mat, a porous material, polyurethanerubber, synthetic rubber, natural rubber, silicones, PDMS, texturedmaterials, and combinations thereof. In one embodiment of the invention,wiping head 230 is a fixed head. In another embodiment, wiping head 230is movable with respect to substrate 110. Alternatively, wiping head 230and substrate 110 may be moved simultaneously with respect to eachother. In still another embodiment, wiping head 230 is rotatable. In afurther embodiment, wiping head 230 is a rotatable wheel.

The step of tangentially contacting a portion 460 (FIG. 7B) of the atleast one coating 420 with wiping head 230 comprises contacting aportion 460 of the at least one coating 420 in a tangential direction210 with a contact surface of wiping head 230. A schematiccross-sectional view of the contact surface of wiping head 230 is shownin FIG. 6. In one embodiment, shown in FIG. 6, the contact surface 240has a predetermined structure, or geometry. In one embodiment, thepredetermined structure comprises at least one prism 280, with the atleast one prism 280 having a predetermined angle 290. The at least oneprism 280 has a geometric profile, such as a pointed profile or tip, asquare profile, a trapezoidal profile, a rounded profile or tip, and thelike. In another embodiment, the predetermined geometry comprises aplurality of prisms 280, wherein the plurality of prisms 280 areseparated from each other by a predetermined pitch 300, as shown in FIG.6. The plurality of prisms may include prisms having the same profile,or prisms having different profiles, arranged in either a random orpredetermined regular order. In one embodiment, pitch 300 is about 50microns. Wiping head 230 has a structure comprising a plurality ofprotrusions, such as, for example, plurality of prisms 280, to applyconcentrated force to portion 460 so as to remove portion 460 andpattern the film. Wiping head protrusions are separated by indentationsfor carrying solvent to the film surface. The film surface is eithermoistened or premoistened by solvent in the liquid phase. In anotherembodiment, the film surface is moistened or premoistened by solvent inthe vapor phase.

In one embodiment of the claimed method, the contact surface furtherincludes at least one sidewall 260 disposed on at least one edge of thecontact surface 240. In another embodiment, the method further includesthe step of premoistening portion 460 (FIG. 7A) prior to wiping portion460 with wiping head 230. The step of wiping the portion 460 with thewiping head to remove the portion 460 of the at least one coating 420from the substrate 410 (FIG. 7A) comprises translating the substrate 410in a predetermined direction with respect to wiping head 230. In anotherembodiment, wiping head 230 wipes the portion 460 in a directionparallel to the predetermined direction. In another embodiment, wipinghead 230 wipes the portion 460 in a direction other than parallel to thepredetermined direction. In another embodiment, the step of providingthe substrate 410 comprises providing a continuous sheet of thesubstrate from a supply roll. In another embodiment the method furtherincludes the step of collecting the continuous sheet on a take-up roll.

In another embodiment of the claimed invention, an apparatus isdisclosed for selectively removing a portion 460 at least one coating420 from a surface of a substrate 410. The apparatus comprises a meansfor supplying the substrate 410 having the at least one coating 420, awiping head 230 for removing a portion 460 of the at least one coating420, wherein the wiping head 230 contacts the at least one coating 420in a tangential direction 210, and a means for collecting the substrateafter removing the portion 460.

In another embodiment of the claimed invention, a wiping head 230 isdisclosed for removing a portion 460 of at least one coating 420disposed on a surface of a substrate 410. The wiping head 230 comprisesa contact surface 240 for contacting and removing portion 460, whereincontact surface 240 contacts portion 460 in a tangential direction 210,and wherein contact surface 240 has a predetermined structure.

Although the examples described hereinabove are for anelectroluminescent device, it is understood that the invention can beused in manufacturing features of other articles and devices, such as,but not limited to, microelectronic devices, photovoltaics, thin filmtransistors, electronic paper and displays, photonic devices,waveguides, microelectromechanical systems (MEMS), microfluidicsdevices, and the like.

While typical embodiments have been set forth for the purpose ofillustration, the foregoing description should not be deemed to be alimitation on the scope of the invention. Accordingly, variousmodifications, adaptations, and alternatives may occur to one skilled inthe art without departing from the spirit and scope of the presentinvention.

1-60. (canceled)
 61. A method of selectively removing at least one coating from a surface of the substrate, the method comprising the steps of: a) providing the substrate, the substrate having the at least one coating disposed on the surface; b) contacting a portion of the at least one coating with a wiping head; and c) wiping the portion with the wiping head in a direction that is tangential to the surface to remove the portion of the at least one coating from the substrate.
 62. The method according to claim 61, wherein the at least one coating is a wet coating.
 63. The method according to claim 61, wherein the at least one coating is a dry coating.
 64. The method according to claim 61, wherein the at least one coating has been baked onto the surface of the substrate.
 65. The method according to claim 61, wherein the wiping head is a dry wiping head.
 66. The method according to claim 61, wherein the wiping head is moistened with a solvent.
 67. The method according to claim 77, wherein the solvent is at least one of water, methanol, ethanol, isopropanol, acetone, toluene, xylene, and combinations thereof.
 68. The method according to claim 61, wherein the wiping head is moistened by injecting the solvent into the head while the head wipes the portion of the at least one coating.
 69. The method according to claim 61, wherein the wiping head comprises at least one of a sponge, an elastomer, a thermoplastic, a thermoset, a fiber mat, a porous material, polyurethane rubber, synthetic rubber, natural rubber, silicones, polydimethylsiloxane, a textured material, and combinations thereof.
 70. The method according to claim 61, wherein the wiping head is a fixed head.
 71. The method according to claim 61, wherein the wiping head is movable with respect to the substrate.
 72. The method according to claim 61, wherein the wiping head is rotatable.
 73. The method according to claim 83, wherein the wiping head is a rotatable wheel.
 74. The method according to claim 61, wherein the step of tangentially contacting a portion of the at least one coating with a wiping head comprises tangentially contacting a portion of the at least one coating with a contact surface of the wiping head, wherein the contact surface has a predetermined structure.
 75. The method according to claim 91 wherein the predetermined structure comprises a plurality of protrusions for applying concentrated force to the surface.
 76. The method according to claim 74, wherein the predetermined structure comprises at least one prism, the at least one prism having a predetermined angle.
 77. The method according to claim 76, wherein the predetermined angle is about 90°.
 78. The method according to claim 76, wherein the predetermined structure comprises a plurality of prisms, wherein the plurality of prisms are separated from each other by a predetermined pitch.
 79. The method according to 78, wherein the pitch is about 50 microns.
 80. The method according to claim 76, wherein the at least one prism has a trapezoidal profile.
 81. The method according to claim 76, wherein the at least one prism has a rounded tip.
 82. The method according to claim 76, wherein the at least one prism has a pointed tip.
 83. The method according to claim 74, wherein the contact surface further includes at least one sidewall disposed on at least one edge of the contact surface.
 84. The method according to claim 61, further including the step of premoistening the portion prior to wiping the portion with the wiping head.
 85. The method according to claim 84, further including the step of premoistening the portion with a vapor solvent.
 86. The method according to claim 84, further including the step of premoistening the portion with a liquid solvent.
 87. The method according to claim 84, further including the step of premoistening a selected area of the coating.
 88. The method according to claim 84, further including the step of premoistening the complete area of the coating.
 89. The method according to claim 61, wherein the step of wiping the portion with the wiping head to remove the portion of the at least one coating from the substrate comprises translating the substrate in a predetermined direction with respect to the wiping head.
 90. The method according to claim 89, wherein the wiping head wipes the portion in a direction parallel to the predetermined direction.
 91. The method according to claim 89, wherein the wiping head wipes the portion in a direction other than parallel to the predetermined direction.
 92. The method according to claim 61, wherein the step of providing the substrate comprises providing a continuous sheet of the substrate.
 93. The method according to claim 92, wherein the step of providing a continuous sheet of the substrate comprises providing a continuous sheet of the substrate from a supply roll.
 94. The method according to claim 92, further including the step of collecting the continuous sheet on a take-up roll.
 95. The method according to claim 61, wherein the step of wiping the portion with the wiping head further comprises a continuous wiping.
 96. The method according to claim 61, wherein the step of wiping the portion with the wiping head further comprises an intermittent wiping.
 97. The method according to claim 61, wherein the substrate comprises at least one of a microelectronic device, a photovoltaic cell, a thin film transistor, electronic paper, electronic display, a photonic device, a waveguide, a microelectromechanical system (MEMS), and a microfluidic device.
 98. An apparatus for selectively removing at least one coating from a surface of a substrate, the apparatus comprising: a) a means for supplying the substrate having the at least one coating; b) a wiping head for removing a portion of the at least one coating, wherein the wiping head tangentially contacts the at least one coating; and c) a means for collecting the substrate after removing the portion. 99-122. (canceled)
 123. A wiping head for removing a portion of at least one coating disposed on a surface of a substrate, the wiping head comprising a contact surface for contacting and removing the portion, wherein the contact surface tangentially contacts the portion, wherein the contact surface has a predetermined structure. 124-131. (canceled) 